CN116486959A - Path planning method, additive manufacturing method and related products - Google Patents

Abstract

The application provides a path planning method, an additive manufacturing method and related products thereof, wherein the path planning method comprises the following steps: acquiring structural parameters of a target structure comprising a first structure and a second structure; generating a plurality of printing curved surfaces according to the structural parameters of the target structure, wherein the printing curved surfaces comprise a first printing curved surface corresponding to the first structure and a second printing curved surface corresponding to the second structure; mapping the first printing curved surface and the second printing curved surface to two-dimensional planes respectively by adopting different mapping functions to obtain a first two-dimensional graph and a second two-dimensional graph; planning filling paths in the first two-dimensional graph and the second two-dimensional graph respectively to obtain a first two-dimensional filling path and a second two-dimensional filling path; mapping the first two-dimensional filling path back to the first printing curved surface to obtain a three-dimensional filling path of the first printing curved surface; and mapping the second two-dimensional filling path back to the second printing curved surface to obtain a three-dimensional filling path of the second printing curved surface. The method and the device can reduce complexity and difficulty of path planning.

Description

Path planning method, additive manufacturing method and related products

Technical Field

The present application relates to the field of material manufacturing, and in particular to a path planning method, an additive manufacturing method and related products.

Background Art

Additive manufacturing technology is relative to subtractive manufacturing. It is based on the principle of layered manufacturing. Starting from a digital model, it realizes the manufacture of three-dimensional solid parts through a layer-by-layer accumulation rather than removal process. According to its molding process, it can be divided into fused deposition modeling (FDM), stereolithography (SLA), powder bed fusion (PBF), etc.

More and more research is beginning to explore the possibility of additive manufacturing of composite materials. Composite materials are designed through two or more material components to achieve complementary performance of different material components, thereby obtaining more superior performance. In particular, composite materials with resin as the matrix and continuous fiber as the reinforcement often have excellent mechanical properties and lightweight characteristics, which makes them widely used in advanced manufacturing fields such as aerospace, automobiles, and ships.

Based on the idea of combining the advantages of composite materials and additive manufacturing technology, some scholars have proposed continuous fiber-reinforced polymer additive manufacturing (CFRP-AM). At the same time, CFRP-AM technology can selectively deposit continuous fiber-reinforced composite materials with spatial distribution, and its finished parts are often lightweight and high-strength, which has attracted widespread attention in the industry. According to different molding processes, CFRP-AM technology can be divided into material extrusion (Material Extrusion, MEX), directed energy deposition (Directed Energy Deposition, DED), laminated bonding (Laminated Objective Manufacturing, LOM), etc.

CFRP-AM technology has a very broad application prospect, but because this technology has only been around for a short time and involves many disciplines, such as digital modeling, electromechanical control, and material science, there are still many challenges. For example, the existing CFRP-AM manufacturing equipment based on a three-degree-of-freedom motion platform is not suitable for manufacturing complex engineering structures with non-planar fiber placement. In addition, due to the significant mechanical anisotropy of continuous fiber reinforced composites, fiber placement path design is one of the key factors affecting the mechanical properties of CFRP-AM process parts. At the same time, multi-degree-of-freedom motion brings more possibilities for fiber placement path design, but also increases the complexity and difficulty of path planning.

Summary of the invention

The present application provides a path planning method, an additive manufacturing method and related products, which can reduce the complexity and difficulty of path planning and meet the filling requirements of different structures.

In a first aspect, the present application provides a path planning method, comprising:

Get the structural parameters of the target structure;

Generating a plurality of printed curved surfaces according to the structural parameters of the target structure, wherein the target structure includes a first structure and a second structure, and the plurality of printed curved surfaces include a first printed curved surface corresponding to the first structure and a second printed curved surface corresponding to the second structure;

Using different mapping functions to map the first printed curved surface and the second printed curved surface to two-dimensional planes respectively, to obtain a first two-dimensional figure and a second two-dimensional figure;

Planning filling paths in the first two-dimensional figure and the second two-dimensional figure respectively to obtain a first two-dimensional filling path and a second two-dimensional filling path;

Mapping the first two-dimensional filling path back to the first printing surface to obtain a three-dimensional filling path of the first printing surface;

The second two-dimensional filling path is mapped back to the second printing surface to obtain a three-dimensional filling path of the second printing surface.

Optionally, respectively planning filling paths in the first two-dimensional graphic and the second two-dimensional graphic to obtain a first two-dimensional filling path and a second two-dimensional filling path includes:

A filling path is planned in the first two-dimensional figure by adopting a complete filling method to obtain a first two-dimensional filling path.

Optionally, the using different mapping functions to map the first printed curved surface and the second printed curved surface to two-dimensional planes respectively to obtain a first two-dimensional graph and a second two-dimensional graph comprises:

When the first printed surface is a developable surface, an isometric mapping function is used to map the first printed surface onto a two-dimensional plane to obtain a first two-dimensional figure; or,

When the first printed surface is not a developable surface, the first printed surface is converted into a combination of at least two developable surfaces, and the at least two developable surfaces are respectively mapped onto a two-dimensional plane using an isometric mapping function to obtain a first two-dimensional figure.

Optionally, the using different mapping functions to map the first printed curved surface and the second printed curved surface to two-dimensional planes respectively to obtain a first two-dimensional graph and a second two-dimensional graph comprises:

Mapping the second printed surface to a two-dimensional plane using a common mapping function to obtain a second two-dimensional figure;

The step of respectively planning filling paths in the first two-dimensional graphic and the second two-dimensional graphic to obtain a first two-dimensional filling path and a second two-dimensional filling path comprises:

A filling path is planned in the second two-dimensional figure to obtain a second filling path with a regular figure.

Optionally, the target structure is a reinforced shell structure, and the reinforced shell structure includes a shell and reinforcing ribs located on the surface of the shell;

The first structure is the shell, and the second structure is the reinforcing rib.

In a second aspect, the present application provides an additive manufacturing method, comprising:

Acquire a three-dimensional filling path of multiple printed surfaces of a target structure according to any one of the path planning methods;

Converting the three-dimensional filling paths of the plurality of printed surfaces into machine motion trajectories respectively;

According to the machine motion trajectory, a multi-axis robot arm is used to drive a terminal printing tool located at the terminal end of the multi-axis robot arm to print a target material on the printing substrate.

Optionally, the three-dimensional filling paths of the plurality of printed surfaces include a first printing path representation, wherein the first printing path representation includes three-dimensional coordinates and normal vectors of a plurality of discrete path points in a printing substrate coordinate system;

The step of converting the three-dimensional filling paths of the plurality of printed curved surfaces into machine motion trajectories respectively comprises:

Acquire a position and posture conversion relationship between a coordinate system of a terminal printing tool and a coordinate system of a robot arm base of the multi-axis robot arm, and a position and posture conversion relationship between a coordinate system of a printing substrate and a coordinate system of the robot arm base;

According to a posture conversion relationship between the coordinate system of the end printing tool and the coordinate system of the robot arm base, converting the first printing path representation into a second printing path representation in the coordinate system of the end printing tool;

According to the position conversion relationship between the coordinate system of the printing substrate and the coordinate system of the robot base, the second printing path representation is converted into a machine motion trajectory in the coordinate system of the robot base.

Optionally, the converting the first printing path representation into a second printing path representation in the coordinate system of the end printing tool according to a posture conversion relationship between the coordinate system of the end printing tool and the coordinate system of the robot arm base includes:

Taking the i-th discrete path point in the first printing path representation as the origin and the unitized normal vector as the Z axis of the coordinate system of the end printing tool, the pose of the i-th discrete path point in the coordinate system of the end printing tool is constructed, and the second printing path representation includes the pose of each discrete path point in the coordinate system of the end printing tool.

Optionally, the target material comprises fiber and resin, and the method further comprises:

Obtain the cross-sectional parameters and printing speed of a single-pass printed sample;

Determining a feed rate of the fiber and a feed rate of the resin according to the cross-sectional parameters and the printing speed;

The method of using the multi-axis mechanical arm to drive a terminal printing tool located at a terminal of the multi-axis mechanical arm to print a target material on the printing substrate comprises:

A target material is printed on the printing substrate according to a feed rate of the fiber and a feed rate of the resin.

Optionally, the method further comprises: obtaining a fiber correction coefficient, and correcting the fiber feed rate according to the fiber correction coefficient.

The method of using a multi-axis mechanical arm to drive a terminal printing tool located at a terminal of the multi-axis mechanical arm to print a target material on the printing substrate includes: printing the fiber according to the corrected fiber feed rate;

and/or,

The method further includes: obtaining a resin correction coefficient, and correcting the resin feed rate according to the resin correction coefficient.

The method of using the multi-axis robot arm to drive a terminal printing tool located at a terminal of the multi-axis robot arm to print a target material on the printing substrate includes: printing the resin according to the corrected resin feed rate.

Optionally, the fiber feed rate after correction is less than or equal to the fiber feed rate before correction, and the resin feed rate after correction is greater than or equal to the resin feed rate before correction.

Optionally, the step of obtaining a pose conversion relationship between a coordinate system of a terminal printing tool and a coordinate system of a robot arm base of the multi-axis robot arm, and a pose conversion relationship between a coordinate system of a printing substrate and a coordinate system of the robot arm base, further includes:

Acquire a first posture conversion relationship, wherein the first posture conversion relationship is a posture conversion relationship of a coordinate system of an end printing tool relative to a coordinate system of a robotic arm end, wherein the robotic arm end is located at the end of a robotic arm fixed to a robotic arm base, and is used to move the end printing tool so that the end printing tool prints material on a printing substrate;

Acquire a second posture conversion relationship, where the second posture conversion relationship is a posture conversion relationship of a coordinate system of the end of the robotic arm relative to a coordinate system of the robotic arm base;

According to the first posture conversion relationship and the second posture conversion relationship, obtaining a posture conversion relationship of the coordinate system of the end printing tool relative to the coordinate system of the robot arm base;

According to the posture conversion relationship between the coordinate system of the end printing tool and the coordinate system of the robot base, the posture conversion relationship between the coordinate system of the printing substrate and the coordinate system of the robot base is obtained.

Optionally, obtaining the first pose conversion relationship includes:

The end printing tool is driven by the robot arm to sequentially contact the same reference point on the printing substrate at least twice in different postures;

Acquire a position transformation relationship between a coordinate system of the end of the robot arm and a coordinate system of the base of the robot arm at each contact;

According to the position conversion relationship between the coordinate system of the end of the robot arm and the base of the robot arm in the at least two contacts, the position vector of the coordinate system of the end printing tool relative to the coordinate system of the end of the robot arm is calculated.

Optionally, obtaining the first pose includes:

Determine three feature points on the end printing tool, and the positional relationship between any two of the three feature points in the coordinate system of the end printing tool, wherein the three feature points are not on the same straight line;

The end printing tool is driven by the mechanical arm so that the three characteristic points on the end printing tool are contacted with the corresponding preset reference points on the printing substrate in sequence;

Respectively obtaining a posture conversion relationship of the end of the robotic arm relative to the robotic arm base when each of the feature points of the end printing tool contacts the corresponding reference point;

According to the positional relationship between any two of the three feature points in the coordinate system of the end printing tool, and the posture transformation relationship of the end of the robotic arm relative to the robotic arm base when each of the feature points of the end printing tool contacts the corresponding reference point, the rotation matrix of the coordinate system of the end printing tool relative to the coordinate system of the end of the robotic arm is calculated.

Optionally, acquiring a posture conversion relationship between the coordinate system of the printing substrate and the coordinate system of the robot base according to the posture of the coordinate system of the end printing tool relative to the coordinate system of the robot base comprises:

Determining three feature points on the printing substrate, and the positional relationship between any two of the three feature points in the coordinate system of the printing substrate, wherein the three feature points are not on the same straight line;

The end printing tool is driven by the mechanical arm to contact the three feature points respectively;

Respectively obtaining a posture conversion relationship between the end of the robot arm and the robot arm base when the end printing tool contacts each of the feature points;

According to the positional relationship between any two of the three feature points in the coordinate system of the printing substrate, and the posture transformation relationship of the end of the robotic arm relative to the robotic arm base when the end printing tool contacts each of the feature points, the posture transformation relationship of the coordinate system of the printing substrate relative to the coordinate system of the robotic arm base is determined.

In a third aspect, the present application provides a path planning device, comprising:

A first acquisition module is used to acquire structural parameters of a target structure;

a generating module, configured to generate a plurality of printing curved surfaces according to the structural parameters of the target structure, wherein the target structure includes a first structure and a second structure, and the plurality of printing curved surfaces include a first printing curved surface corresponding to the first structure and a second printing curved surface corresponding to the second structure;

A mapping module, used to map the first printed curved surface and the second printed curved surface to a two-dimensional plane respectively by using different mapping functions to obtain a first two-dimensional figure and a second two-dimensional figure;

A planning module, used to plan filling paths in the first two-dimensional figure and the second two-dimensional figure respectively, to obtain a first two-dimensional filling path and a second two-dimensional filling path;

The mapping module is further used to map the first two-dimensional filling path back to the first printing surface to obtain a three-dimensional filling path of the first printing surface;

The mapping module is further used to map the second two-dimensional filling path back to the second printing surface to obtain a three-dimensional filling path of the second printing surface.

In a fourth aspect, the present application provides an additive manufacturing device, comprising:

A second acquisition module is used to acquire three-dimensional filling paths of multiple printed surfaces of the target structure;

A conversion module, used to convert the three-dimensional filling paths of the plurality of printing surfaces into machine motion trajectories respectively;

The printing module is used to use a multi-axis mechanical arm to drive a terminal printing tool located at the terminal of the multi-axis mechanical arm to print a target material on the printing substrate according to the machine motion trajectory.

In a fifth aspect, the present application provides a path planning device, comprising a first memory and a first processor, wherein the first memory stores executable code, and when the executable code is processed by the first processor, the first processor can execute any one of the path planning methods described.

In a sixth aspect, the present application provides an additive manufacturing device, comprising a second memory and a second processor, wherein the second memory stores executable code, and when the executable code is processed by the second processor, the second processor can execute any one of the additive manufacturing methods described.

In a seventh aspect, the present application provides a computer-readable storage medium having executable code stored thereon. When the executable code is executed by a processor of an electronic device, the electronic device executes any one of the path planning methods or additive manufacturing methods described.

In the path planning method of the present application, the calculation difficulty is reduced by mapping the three-dimensional surface to a two-dimensional plane and then performing filling path planning; and the printed surfaces of different structures in the target structure are mapped to the two-dimensional plane using different mapping functions, allowing different geometric designs (surface thin shells and reinforcement ribs) and their filling paths to be explored simultaneously, which can meet the filling requirements of different structures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of an embodiment of a path planning method of the present application;

FIG2 is a schematic diagram showing a comparison of two-dimensional graphs obtained by using isometric mapping and commonality mapping on the same surface;

FIG3 is a schematic diagram showing the comparison of zigzag filling paths on a two-dimensional plane and a three-dimensional surface associated by isometric mapping;

FIG4 is a schematic diagram showing a comparison of a fill path based on arc offset on a two-dimensional plane and a three-dimensional curved surface associated by isometric mapping;

FIG5 is a schematic diagram showing a comparison of a fill path based on contour offset on a two-dimensional plane and a three-dimensional surface associated by isometric mapping;

FIG6 is a schematic diagram showing a comparison of a fill pattern based on ±30 degree cross lines on a two-dimensional plane and a three-dimensional curved surface associated by conformal mapping;

FIG7 is a schematic diagram showing a comparison of a fill pattern based on ±45 degree cross lines on a two-dimensional plane and a three-dimensional curved surface associated by conformal mapping;

FIG8 is a schematic diagram showing a comparison of a fill pattern based on ±60 degree cross lines on a two-dimensional plane and a three-dimensional curved surface associated by conformal mapping;

FIG9 is a schematic diagram showing the comparison of the filling pattern based on the elliptical unit on the two-dimensional plane and the three-dimensional curved surface associated by the conformal mapping;

FIG10 is a schematic diagram of an embodiment of an additive manufacturing method in the present application;

FIG11 is a partial structural schematic diagram of an embodiment of an additive manufacturing device of the present application;

FIG12 is a schematic diagram of an embodiment of a method for converting the three-dimensional filling paths of the plurality of printed curved surfaces into machine motion trajectories in the additive manufacturing method of the present application;

FIG13 is a schematic diagram of an embodiment of a calibration method for an additive manufacturing device of the present application;

FIG14 is a schematic diagram of an embodiment of a path planning device of the present application;

FIG15 is a schematic diagram of an embodiment of an additive manufacturing device of the present application;

FIG16 is a schematic diagram of an embodiment of a path planning device of the present application;

FIG. 17 is a schematic diagram of an embodiment of a path planning device of the present application.

DETAILED DESCRIPTION

The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and/or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

It should be understood that although the terms "first", "second", "third", etc. may be used in the present application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Moreover, in practical applications, the objects referred to by the first and second may be the same object or different objects. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

The path planning method in the present application can be used for path planning of continuous fiber reinforced grid structures. The fiber path printing order has a significant impact on manufacturing efficiency and quality. However, the existing continuous fiber path planning algorithms for grid structures lack versatility and can only plan the path of a grid structure of a specific shape. The path planning method proposed in the present application is capable of performing path planning for grid structures of different shapes, has a certain degree of universality, and can ensure the continuity of the filling path and minimize the frequency of fiber cutting, which can improve printing quality and manufacturing efficiency.

As shown in FIG1 , FIG1 is a schematic diagram of an embodiment of a path planning method of the present application. The path planning method includes:

Step S101, obtaining structural parameters of the target structure.

The structural parameters of the target structure may be a variety of parameters that can reflect the structural characteristics of the target structure, and the structural parameters of different types of structures may be the same or different. For example, the target structure is a reinforced shell structure, wherein the reinforced shell structure includes a shell and reinforcing ribs located on the surface of the shell. Optionally, the shell may be thin-walled, usually based on a developable surface; the reinforcing ribs distributed on the shell are usually based on a grid structure layout composed of regular unit cells. The structural parameters of the reinforced shell structure may include a pre-calibrated surface model and a structural normal thickness. For example, the structural parameters of the reinforced shell structure include a surface model, a normal thickness of the shell, a normal thickness of the reinforcing ribs, a single layer thickness, and the like. The structural parameters of the reinforced shell structure may be input by the user, or default parameters may be used.

Optionally, the surface model is a developable surface that can be unfolded onto a plane without any wrinkles or cracks. This ensures the feasibility of unfolding the surface by isometric mapping in subsequent steps. Optionally, the developable surface is described by the following formula:

r(u,v)＝a(u)+vb(u),

Among them, the curve a(u) is called the conductor, b(u) is a straight line vector, called the mother line, and u and v are the orthogonal curvilinear coordinate systems in the parameter space.

Step S102: generating a plurality of printing surfaces according to the structural parameters of the target structure.

The filling path in this application is also used for printing layer by layer, but unlike traditional slicing software, the filling path on each layer in this application is not a two-dimensional path in each two-dimensional slice obtained by traditional slicing software, but a three-dimensional path. Wherein, the target structure includes different first structures and second structures, and the multiple printing surfaces include a first printing surface corresponding to the first structure and a second printing surface corresponding to the second structure.

Before obtaining the filling path on each layer of the target structure, a series of slice layers of the target structure, that is, a series of printed surfaces, can be first constructed by offsetting the surface model in the structure parameters, wherein the series of printed surfaces are divided into different types of surfaces according to different positions, for example, including multiple printed surfaces corresponding to the first structure and multiple printed surfaces corresponding to the second structure. For the sake of description, one of the multiple printed surfaces corresponding to the first structure is referred to as the first printed surface, and one of the multiple printed surfaces corresponding to the second structure is referred to as the second printed surface. Optionally, the surface model used to construct the multiple printed surfaces of the first structure and the surface model used to construct the multiple printed surfaces of the second structure can be the same surface model or different surface models.

Taking the reinforced shell structure as an example, before obtaining the filling path on each layer of the reinforced shell structure, a series of slice layers of the reinforced shell structure can be first constructed by offsetting the surface model in the structural parameters, that is, a series of printed surfaces, wherein the series of printed surfaces are divided into shell surfaces and rib surfaces according to different positions. In one example, the shell surface is generated by the shell surface model along the normal offset distance H1, where H1 = single-layer thickness of the shell structure × number of layers. The rib surface is generated by the rib surface model along the normal offset distance H2, where H2 = single-layer thickness of the rib structure × number of layers. Optionally, the normal offset vector of the shell surface model or the rib surface model can be projected in the horizontal or vertical direction, and corrected by the correlation coefficient of the angle between the normal vector and the horizontal plane to ensure that the single-layer thickness along the normal direction remains unchanged to obtain high printing quality.

Step S103: Use different mapping functions to map the first printed curved surface and the second printed curved surface to two-dimensional planes respectively, to obtain a first two-dimensional graph and a second two-dimensional graph.

For each obtained printed surface, the printed surface is mapped to a two-dimensional plane to plan a filling path for the printed surface on the two-dimensional plane. The first printed surface and the second printed surface are respectively mapped to the two-dimensional plane using different mapping functions to meet the filling requirements of different structures.

For example, in some examples, the first structure needs to adopt a complete filling method to plan the filling path, so the length needs to be maintained within the error range. The first printed surface can be mapped to the two-dimensional plane using an isometric mapping function to obtain a first two-dimensional figure. Although the first printed surface and the first two-dimensional figure associated with the isometric mapping have different shapes, they can be converted into each other through continuous deformation. That is, the first printed surface associated with the isometric mapping and any corresponding curve on the first two-dimensional figure have the same length. Therefore, without changing the single-channel width, the complete filling pattern on the first two-dimensional figure still meets the complete filling requirement after being mapped back to the first printed surface.

Optionally, the first printed surface is a developable surface, which can ensure that there is a corresponding isometric mapping function for the first printed surface. Optionally, when the first printed surface is not a developable surface, or when a single developable surface cannot meet the error requirement, the first printed surface is converted into a combination of at least two developable surfaces, and the at least two developable surfaces are respectively mapped onto a two-dimensional plane using an isometric mapping function to obtain a first two-dimensional figure.

In some examples, when the filling path of the first structure is a regular figure, the first printed surface can be mapped to a two-dimensional plane using a common mapping function to obtain a second two-dimensional figure. Regular figures are usually difficult to fill into complex polygons generated by isometric mapping. Therefore, conformal mapping is used to map the second printed surface to a two-dimensional Euclidean plane, which is a relaxed representation of isometric mapping. The theoretical basis of conformal mapping is that, according to the unification theorem, any closed compact surface with a metric isometrically embedded into one of three typical surfaces through its unification conformal metric: a sphere, a plane, or a hyperbolic space. In addition, conformal mapping is angle-preserving, so it is also called angle-preserving mapping.

As shown in Figure 2, Figure 2 is a comparative schematic diagram of the two-dimensional graphics obtained by isometric mapping and conformal mapping of the same surface. The surface 21 is mapped into an arc strip 22 by the isometric mapping function, and is mapped into a rectangular strip 23 by the conformal mapping function. Among them, the grids in the surface 21, the arc strip 22 and the rectangular strip 23 are all orthogonal lines, which are used to show the relationship between the surfaces before and after mapping. In isometric mapping, any corresponding lines on the surface 21 and the arc strip 22 are the same length; in conformal mapping, any two corresponding curves on the surface 21 and the rectangular strip 23 have the same angle.

In the example where the target structure is a reinforced shell structure, each shell surface and each stiffener surface are obtained, and the shell surface and the stiffener surface are respectively mapped to a two-dimensional plane, so as to plan filling paths for the shell surface and the stiffener surface on the two-dimensional plane. Optionally, the shell surface is mapped to the two-dimensional plane using an isometric mapping function, and the stiffener surface is mapped to the two-dimensional plane using a conformal mapping function. For the stiffener surface, since the stiffeners distributed on the shell are usually based on a grid layout, their typical feature is that they are formed by a regular arrangement of many unit cells defined as rectangles. The use of a conformal mapping function can maintain the local shape of any position on the stiffener surface. This helps to maintain the physical properties of the structure, such as the stiffener angle, which has a significant impact on the mechanical properties of the structure.

Step S104 , planning filling paths in the first two-dimensional graphic and the second two-dimensional graphic respectively, to obtain a first two-dimensional filling path and a second two-dimensional filling path.

A filling pattern generation algorithm for a planar layer printing process may be used to generate a filling pattern, i.e., a filling path, in the first two-dimensional figure and the second two-dimensional figure, respectively. For example, a wire scan, contour offset, Fermat spiral, or other algorithms may be used to generate the filling pattern according to requirements.

Specifically, various filling patterns such as herringbone, contour offset and honeycomb structure can be generated in the first two-dimensional figure (for example, the shell two-dimensional figure in the reinforced shell structure). As shown in Figures 3-5, Figure 3 is a schematic diagram of the comparison of zigzag filling paths on two-dimensional planes and three-dimensional surfaces associated by isometric mapping. Figure 4 is a schematic diagram of the comparison of filling paths based on arc offset on two-dimensional planes and three-dimensional surfaces associated by isometric mapping. Figure 5 is a schematic diagram of the comparison of filling paths based on contour offset on two-dimensional planes and three-dimensional surfaces associated by isometric mapping. It can be seen that the zigzag filling path, the filling path based on arc offset and the filling path based on contour offset can meet the complete filling requirements of the first two-dimensional figure. Among them, the first printed surface associated by isometric mapping and any corresponding curves on the first two-dimensional figure have the same length. For example, the zigzag fill path in Figure 3 is 158.03 mm long on the first printed surface and the first two-dimensional graphic associated with the isometric mapping, the fill path based on arc offset in Figure 4 is 81.85 mm long on the first printed surface and the first two-dimensional graphic associated with the isometric mapping, and the fill path based on contour offset in Figure 5 is 312.39 mm long on the first printed surface and the first two-dimensional graphic associated with the isometric mapping.

In this process, some filling parameters, such as single-pass width and fiber filling angle of zigzag pattern, can be adjusted within a certain range to achieve diversified filling pattern generation.

The second two-dimensional figure generated by conformal mapping (for example, the two-dimensional figure of the stiffener in the reinforced shell structure) is a regular rectangle, so the periodically arranged unit cells can be quickly filled into the two-dimensional figure of the stiffener to generate the stiffeners distributed on the shell, and the periodically arranged unit cells also represent the three-dimensional filling path. As shown in Figures 6-8, Figure 6 is a schematic diagram of the comparison of the filling pattern based on the ±30-degree cross line on the two-dimensional plane and the three-dimensional surface associated with the conformal mapping, Figure 7 is a schematic diagram of the comparison of the filling pattern based on the ±45-degree cross line on the two-dimensional plane and the three-dimensional surface associated with the conformal mapping, and Figure 8 is a schematic diagram of the comparison of the filling pattern based on the ±60-degree cross line on the two-dimensional plane and the three-dimensional surface associated with the conformal mapping. It can be seen that the first printed surface associated with the conformal mapping and any corresponding curve on the first two-dimensional figure have the same angle. The filling pattern is formed by straight lines of different angles that are uniformly distributed and intersecting along the parameter axis (u and v). In this process, the angle and number of the straight lines can be adjusted to produce a variety of grid structures.

In addition, more complex grid structures can be generated by periodically filling multiple basic units, for example, as shown in FIG9, a comparison diagram of a filling pattern based on elliptical units on a two-dimensional plane and a three-dimensional surface associated by conformal mapping. The multiple periodically arranged basic units filled on the two-dimensional plane are still multiple periodically arranged basic units on the three-dimensional surface. Since conformal mapping only preserves the angle but not the length, the three-dimensional pattern obtained by mapping after uniform filling on the two-dimensional surface will be stretched and contracted. Therefore, optionally, the size of each two-dimensional filling unit cell on the two-dimensional plane is adjusted according to the contraction rate at each point to obtain a three-dimensional pattern with uniformly sized units.

Step S105 , mapping the first two-dimensional filling path back to the first printing surface to obtain a three-dimensional filling path of the first printing surface.

Step S106: Map the second two-dimensional filling path back to the second printing surface to obtain a three-dimensional filling path of the second printing surface.

According to the theory of computational conformal geometry, the mapping function f is homeomorphic, that is, the mapping function and its inverse mapping are one-to-one corresponding. Therefore, the first two-dimensional filling path and the second two-dimensional filling path can be mapped back to the three-dimensional printing surface through the inverse mapping relationship. Finally, all the three-dimensional filling paths generated in the first printing surface and the second printing surface are combined and stored in the form of a series of ordered discrete point sets. Optionally, the surface normal vector corresponding to each discrete point is also calculated for robot trajectory generation in machine execution code conversion.

In the path planning method of this application, the calculation difficulty is reduced by mapping the three-dimensional surface to a two-dimensional plane and then performing filling path planning; and the printed surfaces of different structures in the target structure are mapped to the two-dimensional plane using different mapping functions, allowing different geometric designs (curved thin shells and stiffeners) and their filling paths to be explored simultaneously, which can meet the filling requirements of different structures. For example, in the example of the reinforced shell structure, the complete filling requirements of the shell structure and the requirements of using regular unit cells to fill complex surfaces for the stiffener structure can be met at the same time. In addition, a variety of filling path types can be allowed while ensuring a uniform and uniform path width, and at the same time, the significant mechanical anisotropy of fiber-reinforced composite materials is combined, which makes the conformal CFRP-AM process have a stronger performance adjustment capability.

Optionally, the path planning method in the present application can be used for additive manufacturing. An embodiment of the additive manufacturing method in the present application is described below with reference to FIG. 10 . As shown in FIG. 10 , FIG. 10 is a schematic diagram of an embodiment of the additive manufacturing method in the present application. The additive manufacturing method includes:

Step S1001, obtaining three-dimensional filling paths of multiple printing surfaces of a target structure.

Among them, the method for obtaining the three-dimensional filling paths of multiple printing surfaces of the target structure can refer to the above-mentioned path planning method, which will not be repeated here.

Step S1002: converting the three-dimensional filling paths of the plurality of printing surfaces into machine motion trajectories respectively.

The machine motion trajectory required by different additive manufacturing equipment may be different. The structure of the additive manufacturing equipment can be various. In one example, as shown in Figure 11, Figure 11 is a partial structural schematic diagram of an embodiment of the additive manufacturing equipment of the present application. Among them, the additive manufacturing equipment 10 includes a robot arm base 11, a robot arm 12 fixed on the robot arm base 11, and an end printing tool 13 arranged at the end 121 of the robot arm. Optionally, the additive manufacturing equipment also includes a removable printing substrate 14 located within the range of the activity space of the robot arm 12. The robot arm 12 is used to drive the end printing tool 13 to print materials on the printing substrate 14. During the printing process, the multi-axis robot arm is used to drive the end printing tool located at the end of the multi-axis robot arm to print on multiple slice layers in sequence. Generally, the three-dimensional filling paths of the multiple printed surfaces are represented in the coordinate system of the printing substrate, so it is also necessary to convert the three-dimensional filling paths of the multiple printed surfaces into machine motion trajectories in the coordinate system of the robot arm base.

In one example, the three-dimensional filling paths of the plurality of printed surfaces include a first printing path representation, where the first printing path representation includes three-dimensional coordinates and normal vectors of a plurality of discrete path points in a printing substrate coordinate system.

Step S1003: according to the machine motion trajectory, the multi-axis robot arm is used to drive the end printing tool located at the end of the multi-axis robot arm to print the target material.

Optionally, the target material can be a composite material, a resin material, a liquid metal, etc. For example, the target material is a continuous fiber reinforced composite material. The end printing tool on the end of the multi-axis robotic arm can be an end printing tool of a five-axis motion platform or a six-axis robot motion platform, or an 8-degree-of-freedom end printing tool with a six-axis robot plus a dual-axis rotation platform, or a 12-axis end printing tool with dual six-axis robots. Using multi-degree-of-freedom motion to directly manufacture structural non-planar features, compared to traditional processes that limit fibers to a planar layer and cannot enhance the mechanical properties of the structure along the stacking direction, the multi-degree-of-freedom motion of the end printing tool can greatly expand the freedom of fiber layout design, so that the fibers can enhance the mechanical properties of the component along any desired direction, greatly improving the performance of the product. Optionally, the end printing tool can be part of a CFRP-AM manufacturing system or a manufacturing system of other preparation processes, and is not limited here.

There are many methods for converting the three-dimensional filling paths of the plurality of printed surfaces into machine motion trajectories in step S1002. The step S1002 in the embodiment shown in FIG10 is described below with reference to FIG12 .

As shown in FIG. 12 , FIG. 12 is a schematic diagram of an embodiment of a method for converting the three-dimensional filling paths of the plurality of printed surfaces into machine motion trajectories in the additive manufacturing method of the present application. The conversion method includes:

Step S1201, obtaining a posture conversion relationship between a coordinate system of a terminal printing tool and a coordinate system of a robot base, and a posture conversion relationship between a coordinate system of a printing substrate and a coordinate system of the robot base.

The pose conversion relationship between the coordinate system of the end printing tool and the coordinate system of the robot base, and the pose conversion relationship between the coordinate system of the printing substrate and the coordinate system of the robot base can be calibrated in advance by a calibration method and then stored, and the two pose conversion relationships can be obtained by reading the calibration data stored. Alternatively, the two pose conversion relationships can be obtained by real-time calibration.

Therefore, the generated three-dimensional filling paths of multiple printed surfaces can be converted into the coordinate system of the robot arm base for unified description.

Step S1202: converting the first printing path representation into a second printing path representation in the coordinate system of the end printing tool according to a posture conversion relationship between the coordinate system of the end printing tool and the coordinate system of the robot base.

In order to guide the movement of the robot, the generated first printing path representation needs to be converted into a series of ordered poses in the coordinate system of the end printing tool, that is, the position and orientation of the end printing tool. At the same time, during the printing process, the Zi axis of the end printing tool when printing the i-th discrete point is forced to align with the normal vector of the discrete path point. Therefore, the trajectory generation process of the robot is to construct a series of pose descriptions of the coordinate system of the end printing tool relative to the coordinate system of the robot base with the discrete point as the origin and the unitized normal vector as the Zi axis. As for the Xi and Yi axes of the coordinate system of the end printing tool when printing the i-th discrete point, any two orthogonal vectors on the Zi axis normal can be selected. This is because the nozzle tip is circular, and its rotation around the Z axis has little effect on the deposition of any single track.

Step S1203: convert the second printing path representation into a machine motion trajectory in the coordinate system of the robot base according to the posture conversion relationship between the coordinate system of the printing substrate and the coordinate system of the robot base.

Optionally, the projection vector of the X-axis vector of the coordinate system of the printing substrate on the normal plane corresponding to the Z-axis vector of the coordinate system of the end printing tool is unitized to create the Xi-axis vector of the coordinate system of the end printing tool. The Yi-axis vector is calculated by the cross product of the Zi and Xi-axis vectors. Therefore, the transformation matrix of the coordinate system of the end printing tool relative to the coordinate system of the printing substrate is constructed by the three calculated axis vectors and the discrete point coordinates, which can be abbreviated as:

Where i represents the data of the i-th discrete path point. Then, the posture of the constructed end-printing tool is further transformed into the robot base coordinate system, and the transformation matrix is shown as follows:

Among them, B represents the robot arm base, T represents the end printing tool, and S represents the printing substrate.

Step S1204: using a multi-axis robot arm to drive the end printing tool to print the target material according to the machine motion trajectory.

Optionally, the additive manufacturing device further converts the three-dimensional printing path in the coordinate system converted to the coordinate system of the robot base into a machine-readable code. The machine-readable code may include the robot trajectory and the printing material feed rate. Optionally, some key design parameters that have an important impact on the printing quality are adjustable, such as layer thickness, single-pass width, pattern of the filling path, printing speed, etc. Finally, after conversion to a machine-readable code, the machine-readable code is distributed to the coordinate system of the robot and the end printing tool as needed, and high-quality printing is achieved through the good cooperation of the two modules.

The machine motion trajectory is generated into a machine code, which is parsed and distributed to the corresponding module controller at a certain time interval. Optionally, during the operation of the additive manufacturing equipment, the set temperature data is first sent to the co-extrusion controller via serial communication, and the built-in PID control program controls the nozzle to heat to a specified temperature by controlling the on-off frequency of the heating rod. Then, the control instructions corresponding to the movement of the robot arm are sent to the robot arm controller via Ethernet and the movement speed of the end of the robot arm is output to the host at a certain time interval for calculating the composite material feed rate. The calculated composite material feed rate is sent to the end of the co-extrusion via serial communication to update the motor speed in real time to achieve a match between the printing speed and the material feed rate. After each sub-path is printed, the robot arm and the material feeding module stop moving, and the host sends a fiber cutting command to drive the servo to achieve fiber cutting. When all paths are printed, the host sends a termination command, stops the nozzle heating, and moves the robot arm to a safe position, and the user takes out the print.

In one example, the robotic arm uses a UR10e robot. The transformation matrix usually needs to be expressed in the rotation method, which is a more concise vector form. Where [x, y, z] are discrete point coordinates, and [r _x , _ry , r _z ] represents the rotation vector. In addition, based on the motion control method of joint vector θ = [θ ₁ , θ ₂ , ..., θ ₀ ], it is necessary to convert the given TCF pose into 6 joint angles through inverse kinematics. The inverse kinematics problem can be solved by the robot kinematic chain model, i.e., DH parameters, using analytical methods or numerical iteration methods.

To produce high-quality parts, the material extrusion rate needs to be precisely synchronized with the robot arm motion. More specifically, the matching relationship between the robot kinematics and the deposition process parameters along the CFRP-AM printing path needs to be modeled and precisely controlled.

Optionally, the target material includes fibers and resins; in the additive manufacturing method of the present application, cross-sectional parameters and printing speed of a single-pass printed sample are also obtained; and the fiber feed rate and the resin feed rate are determined according to the cross-sectional parameters and the printing speed. For example, a cross section of a single-pass printed sample can be observed using a scanning electron microscope (SEM). The cross section of the manufactured single-pass sample can be represented as a rounded rectangle with a half-wrapped fiber bundle. Alternatively, the single layer thickness (h) and the single pass width (w) can be used to describe the cross-sectional morphology.

Parameters E1 and E2 are used to represent the feed rate of the fiber and resin wire, that is, the length of the wire fed into the print head per unit time. At a given printing speed (v), E1 has a great influence on the collimation and prestress of the deposited fiber, thereby affecting the overall mechanical properties of the printed part. Therefore, optionally, in the additive manufacturing method of the present application, a fiber correction coefficient is also obtained, the fiber feed rate is corrected according to the fiber correction coefficient, and the fiber is printed according to the modified fiber feed rate. Optionally, the fiber correction coefficient is less than or equal to 1, so that the corrected fiber feed rate is less than or equal to the fiber feed rate before correction. In one example, the fiber correction coefficient is set to 0.95-1.0.

Optionally, a resin correction coefficient is also obtained, the resin feed rate is corrected according to the resin correction coefficient, and the resin is printed according to the modified resin feed rate. Optionally, the resin correction coefficient is greater than or equal to 1, so that the corrected resin feed rate is greater than or equal to the resin feed rate before correction. This is because in a multi-layer and multi-channel deposition model, gap areas can be found in the print. In this study, k2 is usually set to 1.0-1.15 to reduce voids. Fewer voids often help improve mechanical properties, but excessive parameter settings can lead to excessive resin accumulation, which is not good for the surface quality of the part.

According to the volume conservation principle, the quantitative relationship between the feed rate and printing speed of composite materials is expressed as follows:

The printing speed v, single layer thickness h, single bead width w, resin wire diameter d _p, and correction coefficients k1 and k2 can be set by the user or by default. In addition, the material feed rate needs to be converted into a control pulse frequency to control the motor rotation rate.

In a specific example, the additive manufacturing equipment includes four main modules: a control host, a six-axis robot motion module, a fiber-resin co-extrusion printing end, and a replaceable prefabricated free-form substrate. The control host is mainly used for pre-processing process planning and motion control. Specifically, the machine execution file is first output through the process planning algorithm, and then the corresponding motion control instructions are sent to the controllers of the robot arm and the co-extrusion end respectively, so as to achieve mutual cooperation between the two and complete the composite structure manufacturing. The six-axis robot arm motion module is used to realize the multi-degree-of-freedom motion of the system. Its high degree of motion flexibility has significant advantages in avoiding collisions and singularities, and can be used to improve the smoothness of the printing path. Optionally, the six-axis robot arm is mounted on an optical vibration isolation platform, with the robot arm base as the center, and its spherical workspace radius is 1300mm, and the end effective working load is 10kg. In addition, the repeatability accuracy of the robot arm is ±0.05mm, and the maximum speed of the center point of the end printing tool is 1000mm/s. The fiber-resin co-extrusion printing module is fixed to the coordinate system of the end of the robot arm, including a fiber feeding device, a resin extruder, a fiber shearing device, a co-extrusion nozzle, and a temperature control device. This printing end is designed and developed in-house, especially the internal flow channel of the co-extrusion nozzle is optimized based on the results of the thermal-flow field coupling simulation to improve the impregnation effect of the fiber inside the molten chamber. The nozzle outlet diameter is 1mm and the corners are rounded to achieve ironing extrusion after material extrusion and avoid fiber scraping. The maximum heating temperature of the nozzle is 300°C, which can meet the applicable requirements of most thermoplastic engineering plastics. The free-form substrate is used to provide an attachment base for the first layer of composite materials to ensure high printing quality. At the same time, it cannot be installed too close to the edge of the robot arm's workspace, because this will increase the possibility of the robot arm reaching the joint limit. In addition, the substrate can be manufactured and reused using various processes.

In some examples, the gap between the tip of the end printing tool and the previous slice layer is an important factor affecting the printing quality. Therefore, the position and orientation of the end printing tool and the printing substrate in the robot base coordinate system are accurately calibrated to ensure that the gap is accurate and uniform on each printed slice layer.

Optionally, the calibration method is used to calibrate the coordinate system of the end printing tool and the coordinate system of the printing substrate relative to the position and orientation in the robot base coordinate system, respectively, to ensure good printing quality. Specifically, as shown in Figure 11, the calibration process is to establish a mathematical description of the position and orientation relationship between the coordinate system of the printing substrate (Substrate Frame, SF) and the center coordinate system (Tool Center Frame, TCF) of the coordinate system of the end printing tool relative to the coordinate system of the robot base (Base Frame, BF). In the calibration method of the present application, in addition to these three coordinate systems, the coordinate system of the end of the robot arm (End Frame, EF) is also introduced to assist in calibration.

Optionally, the robotic arm is a six-axis robotic arm. Optionally, the coordinate system of the end printing tool is used to print continuous fiber reinforced composite materials on the coordinate system of the printing substrate. Optionally, the coordinate system of the end printing tool is a fiber-resin co-extrusion printing nozzle. Optionally, the coordinate system of the printing substrate is replaceable. Optionally, the coordinate system of the printing substrate is a prefabricated free-form substrate. A calibration method for the additive manufacturing device in the present application is exemplified below in conjunction with Figures 11 and 13. As shown in Figure 13, Figure 13 is a schematic diagram of an embodiment of the calibration method for the additive manufacturing device of the present application. The calibration method comprises:

Step S1301, obtaining a first posture conversion relationship, where the first posture is a posture conversion relationship between a coordinate system of a terminal printing tool and a coordinate system of a terminal of a robotic arm.

The pose of the coordinate system of the end printing tool relative to the coordinate system of the end of the robot arm represents the position and orientation of TCF relative to EF. In mathematical models, this pose conversion relationship is usually expressed by a conversion matrix, namely:

Where R is the rotation matrix and P is the translation vector. Let E refer to the coordinate system of the end of the robot arm and T refer to the coordinate system of the end printing tool. Then the transformation matrix It describes the position of the coordinate system of the end printing tool relative to the coordinate system of the end of the robot arm, which includes the rotation matrix and position vector ^E P _T .

In one example, the robotic arm can drive the end of the robotic arm, and then the end of the robotic arm can drive the end printing tool to contact the same reference point located on the printing substrate at least twice in sequence with different postures, and the posture transformation relationship of the coordinate system of the end of the robotic arm relative to the coordinate system of the robotic arm base during each contact is obtained. According to the posture transformation relationship of the coordinate system of the end of the robotic arm relative to the robotic arm base in the at least two contacts, the position vector of the coordinate system of the end printing tool relative to the coordinate system of the end of the robotic arm is calculated.

For example, a cone-shaped reference object is fixed at a suitable position in the robot arm workspace, and the tip of the cone-shaped reference object is used as a reference point. Optionally, the position of the cone-shaped reference object is far away from the edge of the robot arm workspace. Then, the robot arm is controlled to move the end printing tool so that the center of the end printing tool (e.g., the center of the end nozzle) contacts the tip of the cone-shaped reference object multiple times in different postures, for example, at least 4 times. At the i-th contact in the multiple contacts, the rotation matrix is obtained. and position vector ^B P _Ei , where B refers to the coordinate system of the robot base. It can be understood that And ^B P _Ei satisfies:

Since the tip of the cone-shaped reference object is fixed during the _contact process and the base of the robot arm is fixed, ^BPi remains unchanged at each contact, and the position vector ^EPt = (x, y, z) of the coordinate system of the end printing tool relative to the coordinate system of the end of the robot arm remains unchanged. Therefore, by subtracting the above formula (1) obtained at any two contacts, and then combining these equations to obtain a linear equation ^system A* _EPt = _B. For this equation system, by using the linear least squares method, the best fit of the position vector of the coordinate system of the end printing tool relative to the coordinate system of the end of the robot arm can be obtained, that is:

^E P _T =(A ^T A)- ¹ A ^T B

The rotation matrix of the coordinate system of the end printing tool relative to the coordinate system of the end of the robot arm It can be directly obtained from the mechanical design model. Alternatively, another more accurate method is to set feature points related to the coordinate system on the coordinate system of the end printing tool, and use the known relative position relationship of these feature points to obtain the rotation matrix of the coordinate system of the end printing tool relative to the coordinate system of the end of the robot arm.

Specifically, three feature points are determined on the end printing tool, and the positional relationship between any two of the three feature points in the coordinate system of the end printing tool, and the three feature points are not on the same straight line; the end printing tool is driven by the mechanical arm so that the three feature points on the end printing tool contact the corresponding preset reference points on the printing substrate in sequence; the posture transformation relationship of the end of the mechanical arm relative to the base of the mechanical arm when each of the feature points of the end printing tool contacts the corresponding preset reference point is obtained respectively; according to the positional relationship between any two of the three feature points in the coordinate system of the end printing tool, and the posture transformation relationship of the end of the mechanical arm relative to the base of the mechanical arm when each of the feature points of the end printing tool contacts the corresponding preset reference point, the rotation matrix of the coordinate system of the end printing tool relative to the coordinate system of the end of the mechanical arm is calculated. Among them, the preset reference points corresponding to the three feature points can be the same preset reference point or different preset reference points.

The three characteristic points determined on the end printing tool may be the origin in the coordinate system of the end printing tool, any point on one of the axes, and any point on the plane where the axis is located. For example, the three characteristic points determined on the end printing tool may be the origin in the coordinate system of the end printing tool, a point on the X-axis or the Y-axis, and a point on the XY plane.

Step S1302, obtaining a second posture conversion relationship, where the second posture is a posture conversion relationship between a coordinate system of the end of the robotic arm and a coordinate system of the base of the robotic arm.

Optionally, B refers to the robot base, E refers to the robot terminal, and the transformation matrix Describes the position of the coordinate system at the end of the robot relative to the target robot, including the rotation matrix and position vector ^B P _E . Transformation matrix It can be calculated by the forward kinematics model built into the robot controller.

Step S1303: Determine the posture transformation relationship of the coordinate system of the end printing tool relative to the coordinate system of the robot arm base according to the first posture transformation relationship and the second posture transformation relationship.

The transformation matrix of the coordinate system of the end printing tool relative to the coordinate system of the robot base It can be expressed as

Among them, the transformation matrix Describes the position of the coordinate system of the end of the robot relative to the coordinate system of the robot base, which includes the rotation matrix and position vector ^B P _E .

Step S1304: determining a posture conversion relationship between the coordinate system of the printing substrate and the coordinate system of the robot base according to the posture of the coordinate system of the end printing tool relative to the coordinate system of the robot base.

Specifically, three feature point positions are designed on the coordinate system of the printing substrate for auxiliary calibration. For example, the three feature point positions are the origin P0 in the coordinate system of the printing substrate, the offset point P1 on the X-axis, and the arbitrary point P2 on the XY plane. The position vectors of these feature point positions relative to the coordinate system of the robot base are measured by moving the robot arm to make it contact with the center point of the end printing tool (such as the center point of the co-extrusion nozzle), and then combined with the known positional relationship between the feature point positions to quickly construct the transformation matrix of the coordinate system of the end printing tool relative to the coordinate system of the printing substrate.

In an example, the position vector of the feature point position P0 to P1 is normalized to the X-axis vector. The Y-axis vector needs to first calculate the position vector from point P0 to point P2, then calculate the projection vector of the vector on the normal plane corresponding to the X-axis vector and normalize it. Finally, the Z-axis vector is calculated by the vector product of the X-axis vector and the Y-axis vector. Therefore, the constructed transformation matrix is for:

Where X, Y, and Z are the X-axis, Y-axis, and Z-axis vectors described in the coordinate system of the robot base, respectively, and P0 is the origin coordinate of the coordinate system of the printing substrate relative to the coordinate system of the robot base. Optionally, the robot can be controlled to drive the end printing tool to measure multiple times at each feature point position to reduce errors.

In an embodiment of the present application, by obtaining the posture transformation relationship of the coordinate system of the end printing tool relative to the coordinate system of the end of the robot arm, and the posture transformation relationship of the coordinate system of the end of the robot arm relative to the coordinate system of the robot arm base, the posture transformation relationship of the coordinate system of the end printing tool relative to the coordinate system of the robot arm base, and the posture transformation relationship of the coordinate system of the printing substrate relative to the coordinate system of the robot arm base can be calibrated, so that after the planned printing path is obtained, the printing path can be converted to the coordinate system of the robot arm base to ensure good printing quality.

Among them, the calibrated position and posture transformation relationship of the coordinate system of the terminal printing tool relative to the coordinate system of the robot base, and the position and posture transformation relationship of the coordinate system of the printing substrate relative to the coordinate system of the robot base can be stored and reused, and the calibration method of this application can be performed when replacing or repairing a module in the additive manufacturing equipment. Alternatively, the calibration method of this application can also be performed before each printing task is executed, which is not limited here.

The present application also provides a path planning device, as shown in FIG14 , which is a schematic diagram of an embodiment of the path planning device of the present application, and the path planning device 1400 includes:

The first acquisition module 1401 is used to acquire the structural parameters of the target structure;

A generating module 1402 is used to generate a plurality of printing surfaces according to the structural parameters of the target structure, wherein the target structure includes a first structure and a second structure, and the plurality of printing surfaces include a first printing surface corresponding to the first structure and a second printing surface corresponding to the second structure;

A mapping module 1403, configured to map the first printed curved surface and the second printed curved surface to a two-dimensional plane respectively by using different mapping functions to obtain a first two-dimensional graph and a second two-dimensional graph;

A planning module 1404, configured to plan filling paths in the first two-dimensional graph and the second two-dimensional graph respectively, to obtain a first two-dimensional filling path and a second two-dimensional filling path;

The mapping module 1403 is further used to map the first two-dimensional filling path back to the first printing surface to obtain a three-dimensional filling path of the first printing surface;

The mapping module 1403 is further used to map the second two-dimensional filling path back to the second printing surface to obtain a three-dimensional filling path of the second printing surface.

Optionally, the planning module 1404 is specifically configured to plan a filling path in the first two-dimensional figure by adopting a complete filling method to obtain a first two-dimensional filling path.

Optionally, the mapping module 1403 is specifically used for:

When the first printed surface is a developable surface, an isometric mapping function is used to map the first printed surface onto a two-dimensional plane to obtain a first two-dimensional figure; or,

When the first printed surface is not a developable surface, the first printed surface is converted into a combination of at least two developable surfaces, and the at least two developable surfaces are respectively mapped onto a two-dimensional plane using an isometric mapping function to obtain a first two-dimensional figure.

Optionally, the mapping module 1403 is specifically used to: map the second printed surface to a two-dimensional plane using a common mapping function to obtain a second two-dimensional figure;

The planning module 1404 is specifically used to plan a filling path in the second two-dimensional figure to obtain a second filling path with a regular figure.

Optionally, the target structure is a reinforced shell structure, which includes a shell and reinforcing ribs located on a surface of the shell; the first structure is the shell, and the second structure is the reinforcing ribs.

The present application also provides an additive manufacturing device, as shown in FIG15 , which is a schematic diagram of an embodiment of the additive manufacturing device of the present application. The path planning device 1500 includes:

The second acquisition module 1501 is used to acquire three-dimensional filling paths of multiple printed surfaces of the target structure;

A conversion module 1502, used to convert the three-dimensional filling paths of the plurality of printing surfaces into machine motion trajectories respectively;

The printing module 1503 is used to use a multi-axis robot arm to drive a terminal printing tool located at the terminal of the multi-axis robot arm to print a target material on the printing substrate according to the machine motion trajectory.

Optionally, the three-dimensional filling paths of the plurality of printed surfaces include a first printing path representation, wherein the first printing path representation includes three-dimensional coordinates and normal vectors of a plurality of discrete path points in a printing substrate coordinate system;

The conversion module 1502 is specifically used for:

Acquire a position and posture conversion relationship between a coordinate system of a terminal printing tool and a coordinate system of a robot arm base of the multi-axis robot arm, and a position and posture conversion relationship between a coordinate system of a printing substrate and a coordinate system of the robot arm base;

According to a posture conversion relationship between the coordinate system of the end printing tool and the coordinate system of the robot arm base, converting the first printing path representation into a second printing path representation in the coordinate system of the end printing tool;

According to the position conversion relationship between the coordinate system of the printing substrate and the coordinate system of the robot base, the second printing path representation is converted into a machine motion trajectory in the coordinate system of the robot base.

Optionally, the converting the first printing path representation into a second printing path representation in the coordinate system of the end printing tool according to a posture conversion relationship between the coordinate system of the end printing tool and the coordinate system of the robot arm base includes:

Taking the i-th discrete path point in the first printing path representation as the origin and the unitized normal vector as the Z axis of the coordinate system of the end printing tool, the pose of the i-th discrete path point in the coordinate system of the end printing tool is constructed, and the second printing path representation includes the pose of each discrete path point in the coordinate system of the end printing tool.

Optionally, the target material includes fiber and resin, and the material manufacturing device further includes:

A third acquisition module is used to obtain the cross-sectional parameters and printing speed of a single-pass printing sample;

A determination module, configured to determine a feed rate of the fiber and a feed rate of the resin according to the cross-sectional parameters and the printing speed;

When the printing module uses the multi-axis mechanical arm to drive the end printing tool located at the end of the multi-axis mechanical arm to print the target material on the printing substrate, the printing module is specifically used to:

A target material is printed on the printing substrate according to a feed rate of the fiber and a feed rate of the resin.

Optionally, the material manufacturing device further comprises:

a fourth acquisition module, used for acquiring a fiber correction coefficient; and a first correction module, used for correcting the fiber feed rate according to the fiber correction coefficient; the printing module 1503 is specifically used for printing the fiber according to the corrected fiber feed rate; and/or,

The fifth acquisition module is used to acquire the resin correction coefficient, and the second correction module is used to correct the resin feed rate according to the resin correction coefficient. The printing module 1503 is specifically used to print the resin according to the corrected resin feed rate.

Optionally, the fiber feed rate after correction is less than or equal to the fiber feed rate before correction, and the resin feed rate after correction is greater than or equal to the resin feed rate before correction.

Optionally, the additive manufacturing device further includes a calibration module, which is used for obtaining a posture conversion relationship between a coordinate system of a terminal printing tool and a coordinate system of a robot arm base of the multi-axis robot arm, and a posture conversion relationship between a coordinate system of a printing substrate and a coordinate system of the robot arm base before:

Acquire a first pose conversion relationship, wherein the first pose conversion relationship is a pose conversion relationship of a coordinate system of an end printing tool relative to a coordinate system of a robotic arm end, wherein the robotic arm end is located at the end of a robotic arm fixed to a robotic arm base, and is used to move the end printing tool so that the end printing tool prints material on a printing substrate;

Acquire a second posture conversion relationship, where the second posture conversion relationship is a posture conversion relationship of a coordinate system of the end of the robotic arm relative to a coordinate system of the robotic arm base;

Determine a posture transformation relationship of a coordinate system of the end printing tool relative to a coordinate system of a robot arm base according to the first posture transformation relationship and the second posture transformation relationship;

According to the posture conversion relationship between the coordinate system of the end printing tool and the coordinate system of the robot base, the posture conversion relationship between the coordinate system of the printing substrate and the coordinate system of the robot base is determined.

Optionally, obtaining the first pose conversion relationship includes:

The end printing tool is driven by the robot arm to sequentially contact the same reference point on the printing substrate at least twice in different postures;

Acquire a position transformation relationship between a coordinate system of the end of the robot arm and a coordinate system of the base of the robot arm at each contact;

According to the position conversion relationship between the coordinate system of the end of the robot arm and the base of the robot arm in the at least two contacts, the position vector of the coordinate system of the end printing tool relative to the coordinate system of the end of the robot arm is calculated.

Optionally, obtaining the first pose includes:

Determine three feature points on the end printing tool, and the positional relationship between any two of the three feature points in the coordinate system of the end printing tool, wherein the three feature points are not on the same straight line;

The end printing tool is driven by the mechanical arm so that the three characteristic points on the end printing tool are contacted with the corresponding preset reference points on the printing substrate in sequence;

Respectively obtaining a posture conversion relationship of the end of the robotic arm relative to the robotic arm base when each of the feature points of the end printing tool contacts the corresponding reference point;

According to the positional relationship between any two of the three feature points in the coordinate system of the end printing tool, and the posture transformation relationship of the end of the robotic arm relative to the robotic arm base when each of the feature points of the end printing tool contacts the corresponding reference point, the rotation matrix of the coordinate system of the end printing tool relative to the coordinate system of the end of the robotic arm is calculated.

Optionally, acquiring a posture conversion relationship between the coordinate system of the printing substrate and the coordinate system of the robot base according to the posture of the coordinate system of the end printing tool relative to the coordinate system of the robot base comprises:

Determining three feature points on the printing substrate, and the positional relationship between any two of the three feature points in the coordinate system of the printing substrate, wherein the three feature points are not on the same straight line;

The end printing tool is driven by the mechanical arm to contact the three feature points respectively;

Respectively obtaining a posture conversion relationship between the end of the robot arm and the robot arm base when the end printing tool contacts each of the feature points;

According to the positional relationship between any two of the three feature points in the coordinate system of the printing substrate, and the posture transformation relationship of the end of the robotic arm relative to the robotic arm base when the end printing tool contacts each of the feature points, the posture transformation relationship of the coordinate system of the printing substrate relative to the coordinate system of the robotic arm base is determined.

The present application also provides a path planning device, as shown in Figure 16, which is a schematic diagram of an embodiment of the path planning device of the present application. The path planning device 1600 includes a first processor 1601 and a first memory 1602, and the first memory 1602 stores executable code. When the executable code is executed by the first processor 1601, the first processor 1601 executes any one of the above path planning methods.

The present application also provides an additive manufacturing device, as shown in FIG17 , which is a schematic diagram of an embodiment of a path planning device of the present application. The additive manufacturing device 1700 includes a second processor 1701 and a second memory 1702 , and the second memory 1702 stores executable code, and when the executable code is executed by the second processor 1701 , the second processor 1701 executes any one of the above-mentioned additive manufacturing methods.

Optionally, the additive manufacturing equipment also includes a multi-axis robotic arm fixed on the robotic arm base, and an end printing tool located at the end of the multi-axis robotic arm; the multi-axis robotic arm is used to drive the end printing tool to print the target material on the printing substrate.

Alternatively, the present application can also be implemented as a computer-readable storage medium (or non-temporary machine-readable storage medium or machine-readable storage medium) on which executable code (or computer program or computer instruction code) is stored. When the executable code (or computer program or computer instruction code) is executed by a processor of an electronic device (such as an additive manufacturing device), the processor executes part or all of the various steps of the above-mentioned path planning method or additive manufacturing method according to the present application.

The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims (21)

1. A path planning method, characterized in that, comprising: Get the structure parameters of the target structure; generating a plurality of printing curved surfaces according to structural parameters of the target structure, wherein the target structure includes different first structures and second structures, and the plurality of printing curved surfaces include a first printing curved surface corresponding to the first structure and a second printing curved surface corresponding to the second structure; Mapping the first printed curved surface and the second printed curved surface to a two-dimensional plane by using different mapping functions to obtain a first two-dimensional graphic and a second two-dimensional graphic; Planning filling paths in the first two-dimensional figure and the second two-dimensional figure respectively, to obtain a first two-dimensional filling path and a second two-dimensional filling path; mapping the first two-dimensional filling path back to the first printing surface to obtain a three-dimensional filling path of the first printing surface; The second two-dimensional filling path is mapped back to the second printing surface to obtain a three-dimensional filling path of the second printing surface. 2. The method according to claim 1, wherein said planning a filling path in said first two-dimensional figure and said second two-dimensional figure respectively to obtain a first two-dimensional filling path and a second two-dimensional filling path comprises: A filling path is planned in the first two-dimensional graphic in a complete filling manner to obtain a first two-dimensional filling path. 3. The method according to claim 2, wherein said using different mapping functions to map said first printed curved surface and said second printed curved surface to a two-dimensional plane respectively to obtain a first two-dimensional figure and a second two-dimensional figure, comprising: When the first printing curved surface is a developable curved surface, an isometric mapping function is used to map the first printing curved surface to a two-dimensional plane to obtain a first two-dimensional graphic; or, When the first printing curved surface is not a developable curved surface, the first printed curved surface is converted into a combination of at least two developable curved surfaces, and the at least two developable curved surfaces are respectively mapped to a two-dimensional plane by an isometric mapping function to obtain a first two-dimensional figure. 4. The method according to claim 1, wherein said first printing curved surface and the second printing curved surface are respectively mapped to a two-dimensional plane by using different mapping functions to obtain a first two-dimensional figure and a second two-dimensional figure, comprising: Mapping the second printed curved surface to a two-dimensional plane by using a common mapping function to obtain a second two-dimensional graphic; The planning of filling paths in the first two-dimensional graphics and the second two-dimensional graphics respectively to obtain the first two-dimensional filling paths and the second two-dimensional filling paths includes: A filling path is planned in the second two-dimensional figure to obtain a second filling path with a regular figure. 5. The method according to any one of claims 1 to 4, wherein the target structure is a reinforced shell structure, and the reinforced shell structure includes a shell and reinforcing ribs on the surface of the shell; The first structure is the shell, and the second structure is the reinforcing rib. 6. A method for additive manufacturing, comprising: According to the method described in any one of claims 1 to 5, the three-dimensional filling paths of multiple printing curved surfaces of the target structure are obtained; Converting the three-dimensional filling paths of the plurality of printing surfaces into machine motion trajectories respectively; According to the motion trajectory of the machine, the multi-axis mechanical arm is used to drive the end printing tool located at the end of the multi-axis mechanical arm to print the target material on the printing substrate. 7. The method according to claim 6, wherein the three-dimensional filling paths of the plurality of printing curved surfaces include a first printing path representation, and the first printing path representation includes three-dimensional coordinates and normal vectors of a plurality of discrete path points in the printing base coordinate system; The converting the three-dimensional filling paths of the plurality of printed curved surfaces into machine motion trajectories respectively includes: Obtaining the pose transformation relationship of the coordinate system of the terminal printing tool relative to the coordinate system of the robot base of the multi-axis robot arm, and the pose transformation relationship of the coordinate system of the printing substrate relative to the coordinate system of the robot base; converting the first printing path representation into a second printing path representation under the coordinate system of the end printing tool according to the pose transformation relationship of the coordinate system of the end printing tool relative to the coordinate system of the manipulator base; According to the pose transformation relationship of the coordinate system of the printing substrate relative to the coordinate system of the manipulator base, the second printing path representation is transformed into a machine motion track in the coordinate system of the manipulator base. 8. The method according to claim 7, wherein, according to the pose transformation relationship between the coordinate system of the terminal printing tool and the coordinate system of the manipulator base, converting the first printing path representation into a second printing path representation under the coordinate system of the terminal printing tool comprises: Taking the i-th discrete path point in the first printing path representation as the origin, and using the normal vector as the Z-axis of the coordinate system of the end printing tool to construct the pose of the i-th discrete path point in the coordinate system of the end printing tool, the second printing path representation includes the pose of each discrete path point in the coordinate system of the end printing tool. 9. The method according to claim 7 or 8, wherein the target material comprises fibers and resins, the method further comprising: Obtain the cross-sectional parameters and printing speed of the single-pass printing sample; determining a feed rate of the fiber and a feed rate of the resin according to the cross-sectional parameter and the printing speed; The use of the multi-axis manipulator to drive the end printing tool located on the end of the multi-axis manipulator to print the target material on the printing substrate includes: A target material is printed on the printing substrate according to the feed rate of the fibers and the feed rate of the resin. 10. The method according to claim 9, further comprising: obtaining a fiber correction factor, and correcting the fiber feed rate according to the fiber correction factor, Using a multi-axis robot arm to drive an end printing tool located at the end of the multi-axis robot arm to print the target material on the printing substrate includes: printing the fiber according to the corrected fiber feed rate; and / or, The method further includes: obtaining a resin correction coefficient, and correcting the resin feed rate according to the resin correction coefficient, Using the multi-axis robot arm to drive the end printing tool located at the end of the multi-axis robot arm to print the target material on the printing substrate includes: printing the resin according to the corrected resin feed rate. 11. The method according to claim 10, wherein the corrected fiber feed rate is less than or equal to the fiber feed rate before correction, and the corrected resin feed rate is greater than or equal to the resin feed rate before correction. 12. The method according to any one of claims 9 to 11, wherein the acquisition of the pose transformation relationship of the coordinate system of the terminal printing tool relative to the coordinate system of the robotic arm base of the multi-axis robotic arm, and the pose transformation relationship of the coordinate system of the printing substrate relative to the coordinate system of the robotic arm base, also includes: Obtaining a first pose conversion relationship, the first pose conversion relationship is a pose conversion relationship of the coordinate system of the end printing tool relative to the coordinate system of the end of the mechanical arm, wherein the end of the mechanical arm is located at the end of the mechanical arm fixed on the base of the mechanical arm, and is used to move the end printing tool so that the end printing tool prints materials on the printing substrate; Obtaining a second pose transformation relationship, where the second pose transformation relationship is a pose transformation relation of the coordinate system at the end of the manipulator relative to the coordinate system of the base of the manipulator; According to the first pose transformation relation and the second pose transformation relation, determine the pose transformation relation of the coordinate system of the end printing tool relative to the coordinate system of the manipulator base; According to the pose transformation relationship between the coordinate system of the terminal printing tool and the coordinate system of the manipulator base, determine the pose transformation relationship of the coordinate system of the printing base relative to the coordinate system of the manipulator base. 13. The method according to claim 12, wherein said obtaining the first pose conversion relationship comprises: The end printing tool is driven by the mechanical arm to make at least two contacts with the same reference point on the printing substrate sequentially in different postures; Obtaining the pose transformation relationship of the coordinate system at the end of the robotic arm relative to the coordinate system at the base of the robotic arm at each contact; calculating a position vector of the coordinate system of the end printing tool relative to the coordinate system of the end of the mechanical arm according to the pose transformation relationship of the coordinate system of the end of the mechanical arm relative to the base of the mechanical arm in the at least two contacts. 14. The method according to claim 12, wherein said obtaining the first pose comprises: Determining three feature points on the end printing tool, and the positional relationship of any two of the three feature points in the coordinate system of the end printing tool, the three feature points are not on the same straight line; Driving the end printing tool by the mechanical arm, so that the three feature points on the end printing tool are sequentially in contact with the corresponding preset reference points on the printing substrate; Respectively acquiring the pose transformation relationship of the end of the mechanical arm relative to the base of the mechanical arm when each of the feature points of the end printing tool is in contact with the corresponding reference point; According to the position relationship of any two of the three feature points in the coordinate system of the end printing tool, and the pose transformation relationship of the end of the mechanical arm relative to the base of the mechanical arm when each of the feature points of the end printing tool is in contact with the corresponding reference point, calculate the rotation matrix of the coordinate system of the end printing tool relative to the coordinate system of the end of the mechanical arm. 15. The method according to claim 12, wherein, according to the pose of the coordinate system of the terminal printing tool relative to the coordinate system of the manipulator base, obtaining the pose transformation relationship of the coordinate system of the printing base relative to the coordinate system of the manipulator base comprises: Determining three feature points on the printing base, and the positional relationship of any two of the three feature points in the coordinate system of the printing base, the three feature points are not on the same straight line; driving the end printing tool to contact the three feature points through the multi-axis mechanical arm; Respectively acquiring the pose transformation relationship of the end of the robotic arm relative to the base of the robotic arm when the end printing tool is in contact with each of the feature points; According to the positional relationship of any two of the three feature points in the coordinate system of the printing substrate, and the pose transformation relationship of the end of the mechanical arm relative to the base of the robotic arm when the terminal printing tool contacts each of the feature points, the pose transformation relationship of the coordinate system of the printing substrate relative to the coordinate system of the robotic arm base is determined. 16. A path planning device, characterized in that it comprises: The first obtaining module is used to obtain the structural parameters of the target structure; A generating module, configured to generate a plurality of printed curved surfaces according to structural parameters of the target structure, wherein the target structure includes different first structures and second structures, and the plurality of printed curved surfaces includes a first printed curved surface corresponding to the first structure and a second printed curved surface corresponding to the second structure; A mapping module, configured to use different mapping functions to respectively map the first printed curved surface and the second printed curved surface to a two-dimensional plane to obtain a first two-dimensional graphic and a second two-dimensional graphic; A planning module, configured to plan filling paths in the first two-dimensional graphic and the second two-dimensional graphic, respectively, to obtain the first two-dimensional filling path and the second two-dimensional filling path; The mapping module is further configured to map the first two-dimensional filling path back to the first printing surface to obtain a three-dimensional filling path of the first printing surface; The mapping module is further configured to map the second two-dimensional filling path back to the second printing surface to obtain a three-dimensional filling path of the second printing surface. 17. An additive manufacturing device, characterized in that it comprises: The second acquisition module is used to acquire the three-dimensional filling paths of multiple printing surfaces of the target structure; A conversion module, configured to convert the three-dimensional filling paths of the plurality of printing surfaces into machine motion trajectories respectively; The printing module is configured to use the multi-axis manipulator to drive the terminal printing tool located at the end of the multi-axis manipulator to print the target material on the printing substrate according to the movement track of the machine. 18. A path planning device, comprising a first memory and a second processor, executable code is stored on the first memory, and when the executable code is processed by the first processor, the first processor can be made to execute the method according to any one of claims 1 to 5. 19. An additive manufacturing device, characterized in that it comprises a second memory and a second processor, executable code is stored on the second memory, and when the executable code is processed by the second processor, the second processor can be made to execute the method according to any one of claims 6 to 15. 20. The additive manufacturing equipment according to claim 19, further comprising a multi-axis manipulator fixed on the base of the manipulator, and an end printing tool located at the end of the multi-axis manipulator; The multi-axis mechanical arm is used to drive the terminal printing tool to print target materials on the printing substrate. 21. A computer-readable storage medium, characterized in that executable code is stored, and when the executable code is executed by a processor of the electronic device, the electronic device is made to execute the path planning method according to any one of claims 1 to 5, or execute the additive manufacturing method according to any one of claims 6 to 15.